With headsets solely for sound there is little problem in maintaining the two earphones on opposite sides of the head. Typically this has been done by mounting the two earphones at opposite ends of a resilient arch which, in use, extends over the user's head. More recently, however, the demand has grown for a headset which will also--or exclusively--display visual imagery. In flight simulators this has taken the form of a helmet providing a transparent visor through which the user looks at a screen. Computer generated images are projected onto the visor so as to be superimposed on the view of the screen. A more recent development has been a demand for a helmet which restricts the view of the wearer exclusively to closed circuit television images. Such helmets are used in space research and are worn by personnel monitoring and controlling the activity of robots at remote locations. A yet more recent development has been the need for a similar helmet to present computer generated images to the eyes of the wearer, e.g. by means of two miniature VDU's mounted on the helmet, in the experience of "virtual reality".
Such a helmet or visor should be firmly held on the head, so that it will not be disturbed by rapid movements of the wearer or an accidental knock, but not in such a way that placing it on the head--or more importantly removing it--is at all difficult. The traditional chin-strap is unsuitable. It is unsightly and restricting and does not readily provide an easily accessible quick-release facility.